The molecular genetics of color vision and color blindness

Recent reports from several laboratories have changed our thinking about the molecular genetics of normal color vision and color blindness. The impact of these new findings can be best appreciated by examining them in the context of the historical development of color vision theory.     

Black-headed gulls are more wary of people dressed in red: a test of the concealment color hypothesis

Journal of Ethology - Increased urbanization leads to the modification of animal behavior, including the changes of antipredator behavior in birds. Generally, one of the methods is to focus on...     

通过调查探讨色盲、色弱与正常色觉的遗传关系

通过对贵州省贞丰县一个满族色盲家系的调查和分析,简单探讨了色盲、色弱与正常色觉的遗传关系,提高对此类遗传病进一步的认识,以及用于生物学教学。     

Population heterogeneity and color stimulus heterogeneity in agent-based color categorization

Investigating the interactions between universal and culturally specific influences on color categorization across individuals and cultures has proven to be a challenge for human color categorization and naming research. The present article simulates the evolution of color lexicons to evaluate the role of two realistic constraints found in the human phenomenon: (i) heterogeneous observer populations and (ii) heterogeneous color stimuli. Such constraints, idealized and implemented as agent categorization and communication games, produce interesting and unexpected consequences for stable categorization solutions evolved and shared by agent populations. We find that the presence of a small fraction of color deficient agents in a population, or the presence of a “region of increased salience” in the color stimulus space, break rotational symmetry in population categorization solutions, and confine color category boundaries to a subset of available locations. Further, these heterogeneities, each in a different, predictable, way, might lead to a change of category number and size. In addition, the concurrent presence of both types of heterogeneity gives rise to novel constrained solutions which optimize the success rate of categorization and communication games. Implications of these agent-based results for psychological theories of color categorization and the evolution of color naming systems in human societies are discussed.     

Quantitative and qualitative analysis of stain color using RGB computer color specification

OBJECTIVE: To establish standardized Papanicolaou stain for cytology using RGB color specification. This new method was formerly used in DTP software application for computer color specification. STUDY DESIGN: RGB color specification was taken from a color film, optical constituents of which were made into computer software. Cell samples used in this study were from 100 sputum specimens stained with Papanicolaou stain. We analyzed the color tone of the cytoplasm of squamous cells in the smear. RESULTS: The R and B value of eosinophilic cells were demonstrated statistically by different values between normal, borderline atypical and malignant squamous cells. G and B values of light green-philic cells demonstrated a statistical difference between normal, borderline atypical and malignant squamous cells. No significant differences were found in RGB value between normal, borderline atypical and malignant squamous orangeophilic cells. CONCLUSION: Using our own method of analyzing Papanicolaou-stained sputum, a new quantitative and qualitative analysis of stain color for standardized Papanicolaou stain was introduced.     

Cost and color of photosynthesis

The question of why plants are green has been revisited in several articles recently. A common theme in the discussions is to explain why photosynthesis appears to absorb less of the available green sunlight than expected. The expectation is incorrect, however, because it fails to take the energy cost of the photosynthetic apparatus into account. Depending on that cost, the red absorption band of the chlorophylls may be closely optimized to provide maximum growth power. The optimization predicts a strong influence of Fraunhofer lines in the solar irradiance on the spectral shape of the optimized absorption band, which appears to be correct. It does not predict any absorption at other wavelengths.     

Macroecology and people

A macroecological perspective has become recognised as an important component of ecological studies, serving particularly to crystallise the notion that processes operating at large spatial (geographic) and temporal scales often play important roles in shaping species assemblages and communities at more local scales. However, within the field, consideration has been surprisingly lacking of the influence of humans in shaping macroecological patterns, the determinants of those patterns, or their consequences for local assemblages and communities. Here I briefly review the reasons why this might be so, and the possible interactions between macroecology and people, and suggest some simple steps for exploring this issue.     

Statistical and molecular analyses of evolutionary significance of red-green color vision and color blindness in vertebrates

Red-green color vision is strongly suspected to enhance the survival of its possessors. Despite being red-green color blind, however, many species have successfully competed in nature, which brings into question the evolutionary advantage of achieving red-green color vision. Here, we propose a new method of identifying positive selection at individual amino acid sites with the premise that if positive Darwinian selection has driven the evolution of the protein under consideration, then it should be found mostly at the branches in the phylogenetic tree where its function had changed. The statistical and molecular methods have been applied to 29 visual pigments with the wavelengths of maximal absorption at approximately 510-540 nm (green- or middle wavelength-sensitive [MWS] pigments) and at approximately 560 nm (red- or long wavelength-sensitive [LWS] pigments), which are sampled from a diverse range of vertebrate species. The results show that the MWS pigments are positively selected through amino acid replacements S180A, Y277F, and T285A and that the LWS pigments have been subjected to strong evolutionary conservation. The fact that these positively selected M/LWS pigments are found not only in animals with red-green color vision but also in those with red-green color blindness strongly suggests that both red-green color vision and color blindness have undergone adaptive evolution independently in different species.     

接枝共聚法合成多彩水晶花泥

采用水溶性引发剂,以N'N'-亚甲基双丙烯基酰胺为交联剂,表面活性剂为助剂进行丙烯酸和彩色聚丙烯酸脂接枝共聚,合成多彩水晶花泥。制得的共聚物可吸水100倍以上,形成水凝胶呈水晶多棱结构,色彩艳丽且色泽牢固、不溶于水、无毒、无污染,可用于家庭花卉无土培养、室内插花装饰等。本文讨论引发剂、交联剂、助剂等合成条件对共聚物性能的影响。     

Hair color measurement and variation

Pigmentation of hair in humans has been investigated by medical scientists, anthropologists and, more recently, by forensic scientists. In every investigation, hair color must first be defined by the researchers. Subjective color assessment inhibits the reproducibility of experiments and the direct comparison of results. The aim of this study was to objectively measure human hair color and examine the variation found in a population with European ancestry, using the CIE L*a*b* color space. Observer-perceived hair colors were compared with self-reported hair colors and the color as measured by reflective spectrophotometry of 132 subjects of European ancestry. The presented data show that self-reported hair colors and observer-reported colors are similar; however, these categories are not necessarily the best way to categorize hair color for quantitative research. Using a two-step cluster analysis, hair color can be divided into categories or clusters based on spectrophotometric measurements in the CIE L*a*b* color space and these clusters can be well discriminated from each other. This separation is primarily based on the b* (yellow) color component and the clusters show agreement to observer-reported colors. This study illustrates the possibilities for and necessity of objectively defining the hair color phenotype for various downstream applications.